Water Heaters and Title 24

Gas or Electric?﻿

By a sizeable majority, most households in the U.S. use natural gas to heat water. Other fuel types used to heat water include electricity, propane, and heating oil. A typical gas storage water
heater has an Energy Factor (efficiency rating) of about 0.6, while a typical electric storage water heater will be rated about 0.9. Based on these Energy Factors it would seem an electric water
heater uses less energy. Actually the opposite is true, here's why:﻿

Source Energy

It takes about three times as much source energy (this includes the energy needed to generate and distribute a fuel) to deliver electricity to a home compared to
natural gas. This is because only about 1/3 of the fuel energy burned at the utility's power plant actually reaches a home in the form of electricity. The rest is lost due to inefficiency at the
power plant and over power lines. Therefore, an electric water heater that appears to be 50% “better” than a gas one (0.9 Energy Factor versus 0.6 Energy Factor) actually uses much more (source)
energy than the gas water heater. It is for this reason that when performance modeling a new electric water heater for Title 24 compliance there is a significant penalty.